EFFECTS OF DEUTERATION AND CRYOSOLVENTS ON THE ENERGY TRANSDUCTION INPRIMARY PHOTOSYNTHESIS

The effects of cryosolvents and D2O/H2O substitution on the reaction c enters (RCs) isolated from photosynthetic bacteria were studied with r espect to the role of intraprotein hydrogen bonds in the primary photo synthetic electron transfer. As a result of such treatment of RCs, the charge separation rate between the photoactive bacteriochlorophyll (P -2 dimer) and bacteriopheopytin and the rate of electron transfer to t he primary quinone slowed down. The energy migration rate from bacteri opheophytin (BPhM) nonactive in electron transport to P-2 decreased as well. Although cryosolvents can shift the redox potential of the phot oactive pigment, there is no direct correlation between the P-2 potent ial and effects of these modifying agents on photosynthetic process in RCs occurring with the participation of P-2 The removal of H subunit from the pigment-protein complex results in the pronounced weakening o f the dimethylsulphoxide modifying effects on RC hydrogen bonds. The r ole of structural and dynamic state in the functioning of the photosyn thetic bacteria Res is analysed. Relaxation processes in purple bacter ia RCs accompaning the primary picosecond steps of enetgy transformati on proceed with the participation of small proton-containing molecular groups in the immediate surrounding of electron transfer carriers. In this paper, we present results concerning mechanisms of primary photo synthetic steps, which for a number of years have been studied at the Department of Biophysics and initiated by A.A. Krasnovsky. This paper is dedicated to the memory of our teacher prof. A.A. Krasnovsky.